I really didn't have a problem with Iron Man 2, thought it wasn't as good as the first, but I still enjoyed it. I mean, fuck, it had Scarlet Johanson and all her boob-filled glory. I thought Mickey Rourke did a pretty good job too.
Whiplash is just a shockingly bad villain, that was the issue with Ironman II.
But looking at the third one, Marvel marketted as an adaptation of The Extremist but from any trailer I've seen, doesn't come across at all like the The Extremist Arc unless the only thing which is adapted is the Extremist mutation virus...